The present invention relates to failsafe operation of controller components introduced between a controller host or first device and a tool or second device. In particular, it relates to establishing a direct connection between the first and second device upon failure of a controller that mediates data transfers between the first and second device. One environment in which this invention is useful is a semiconductor manufacturing fab having a host and tools/sensors, into which an intelligent controller is added between using a controller to mediate communications among a tool, sensors associated with the tool and data users, such as a host system or distributed processors.
Moore's law promises exponential growth in computer power at diminishing prices. This dynamic growth of processing power might lead one to think that semiconductor device manufacturing would be an adventuresome business, like wild-catting for oil. Just the opposite is true. Because manufacturing batches are very valuable and manufacturing processes are sensitive to even small mistakes, semiconductor device manufacturing is a conservative business. Qualification cycles and standards for new equipment and modifications of old equipment are lengthy and demanding. Even a small change is vetted extensively, before being released to production.
Key components used by a fab in semiconductor manufacturing include tools (e.g., deposition chambers, reactors), sensors that monitor the tools (e.g., FTIR sensors, mass spectrographs, thermocouples) and hosts or distributed processors that store and analyze data from the sensors regarding tool operation.
A prior application described a transparent method of listening to data from the sensors and providing it to the hosts or distributed processors using high speed and error-resistant technologies such as TCP/IP over Ethernet. The prior application was by inventors Uzi Lev-Ami and Yossef Ilan Reich, “Method and Apparatus for Monitoring Host to Tool Communications,” application Ser. No. 09/935,213, filed on 22 Aug. 2001, which is incorporated by reference. The prior application describes a listening post that could eavesdrop on serial communications from a tool or sensor using an optically isolated connector. Using the eavesdropping approach, one could prove that the fab communications and data collection infrastructure could be upgraded without requiring modification of tools or sensors, at a low risk. The upgrade feasibility could be demonstrated without dismantling the incumbent communications infrastructure.
The next revolution in fab instrumentation and backend analysis capabilities will involve adding intelligent controllers to mediate communications between the tools and sensors, on one side of the controllers, and tool hosts or distributed processors, on the other side, without needing to replace or change the analytical characteristics of the sensors. Increased processor power and decreased storage cost create opportunities for configurations that would not previously have been practical in a fab environment. A second prior application by inventors Uzi Lev-Ami, Guenter Sifnatsch and Mark Attwood, entitled “Controller and Method to Mediate Data Collection from Smart Sensors for Fab Applications”, U.S. patent application Ser. No. 10/819,903 filed on 7 Apr. 2004, describes an intelligent controller with various capabilities.
An opportunity arises to complement the analytical features of an intelligent controller, or any other network attached device that mediates communications between two other devices which are capable of communicating directly, with a failsafe switch that directly links the other devices, if the intermediate device fails or hangs. Better, more reliable and confidence inspiring installations of intermediate devices may result.